Vane pump

ABSTRACT

A vane pump includes slits formed in a base portion of a rotary unit rotating in a casing and extend radially from a rotation axis of a rotary unit to be opened outwardly in a radial direction, a vane received in each of the slits to be protruded from or retreated into the slit, an annular chamber formed around the base portion in the casing and pump rooms formed by defining the annular chamber by using the vanes. The vane pump is operated to discharge fluid sucked into an associated pump room by rotating the rotary unit and thereby periodically increasing or reducing volume of the pump rooms. The vane pump further includes a fluid force generating portion provided on at least one of the rotary unit and the casing to generate fluid force to the upper side in an axial direction of the rotation axis by rotation of the rotary unit.

FIELD OF THE INVENTION

The present invention relates to a vane pump.

BACKGROUND OF THE INVENTION

A rotary type compressor including a conventional vane pump is disclosed in Japanese patent Laid-open Application No. S64-77783. The disclosed rotary type compressor has a space of a substantially constant height formed by structural parts of a casing stacked in the rotation axis direction of a cylindrical rotary unit. The rotary unit and vanes are accommodated in the space. The vanes are inserted into slits which are radially formed in the rotary unit in such a way as to protrude from and be retracted into the slits. When the rotary unit is rotated, the volumes of a plurality of pump chamber divided by the vanes are periodically increased or reduced, so that fluid is sucked into and discharged from the pump chamber.

In the above-described compressor, when the height of the accommodating space is greater than the thickness of the rotary unit or the vanes, the rotary unit or the vanes are axially reciprocated, so that noises can be generated due to an increase of vibration, wear can be accelerated and/or leakage can be increased, resulting in poor pump efficiency. Such problems can be solved by individually measuring the thicknesses of the rotary units and vanes and the heights of the accommodating spaces and assembling the parts having matching dimensions, leading to time consuming assembly.

SUMMARY OF THE INVENTION

In view of the above, the present invention provides a vane pump capable of reducing the axial reciprocating motion of a rotary unit or vanes thereof.

In accordance with an embodiment of the present invention, there is provided a vane pump including: a plurality of slits which are formed in a base portion of a rotary unit rotating in a casing and extend radially from a rotation axis of a rotary unit to be opened outwardly in a radial direction; a vane received in each of the slits to be protruded from or retreated into the slit; an annular chamber formed around the base portion in the casing; a plurality of pump rooms formed by defining the annular chamber by using the plurality of vanes, the vane pump being operated to discharge fluid sucked into an associated pump room by rotating the rotary unit and thereby periodically increasing or reducing volume of the pump rooms; and a fluid force generating portion provided on at least one of the rotary unit and the casing to generate fluid force to the upper side in an axial direction of the rotation axis by rotation of the rotary unit.

With such configuration, the rotary unit is pressed to the upper side in the axial direction in the casing by fluid force generated by the rotation of the rotary unit, thus preventing the rotary unit from reciprocating axially in the casing.

A guide wall may be provided on the rotary unit and placed on the lower side in the axial direction of the rotation axis to be in sliding contact with an associated vane.

With such configuration, the guide wall limits the range in which the vanes may reciprocate in the axial direction.

The vane pump may further includes a thrust support unit for slidably supporting the rotary unit against the casing, the rotary unit being rotated by the fluid force applied to the upper side in the axial direction, wherein a diameter of a sliding portion of the thrust support unit is smaller than a diameter of the base portion.

With such configuration, the area of a range in which the rotary unit and the casing slide at the upper side in the axial direction is formed to be small, thus preventing sliding resistance from increasing.

The fluid force generating portion may be provided on the rotary unit, and includes a slanting surface which is inclined with respect to a rotating direction of the rotary unit.

With such configuration, the slanting surface is formed on the rotary unit, thus allowing the fluid force generating portion to be obtained in a relatively simple construction.

The fluid force generating portion may preferably be provided on the rotary unit, and includes a wing brought into contact with a counter flow of the fluid resulting from rotation of the rotary unit.

With such configuration, the wing is provided on the rotary unit, thus more reliably generating fluid force.

The fluid force generating portion may be provided on the rotary unit, and includes a spiral projection or groove formed around the rotation axis.

With such configuration, the spiral projection or groove is formed on the rotary unit, thus allowing the fluid force generating portion to be obtained in a relatively simple configuration.

The fluid force generating portion may preferably be provided on the casing, and includes a protrusion which is opposite to the rotary unit in such a way as to protrude towards the rotary unit. The fluid force generating portion is provided on the casing, and comprises a protrusion which is opposite to the rotary unit in such a way as to protrude towards the rotary unit.

With such configuration, the protruding portion is provided on the casing, thus allowing the fluid force generating portion to be obtained in a relatively simple configuration.

Preferably, the rotary unit includes a cylindrical skirt portion which is concentric with the rotation axis and protrudes towards the lower side in the axial direction, and a cylindrical gap is formed between the skirt portion and the casing.

With such configuration, the cylindrical, annular gap having a predetermined length in the axial direction can be formed in the outer or inner circumference of a skirt portion. Thus, by appropriately setting the length of the gap and a clearance, leakage flow rate of the working fluid between the lower side of the rotary unit in the axial direction and the casing can be reduced. Further, the gap is formed to be concentric with a rotation axis. Thus, even when the rotary unit moves to the upper side in the axial direction, the length of the associated gap is ensured, thus reducing leakage flow rate of the fluid.

The vane pump may further include a magnetized portion provided on the skirt portion; a stator core including a coil provided inside the skirt portion; and a motor having the magnetized portion and the stator core which are arranged in a radial direction of the rotation axis of the rotary unit to be spaced apart from each other.

With such configuration, the magnetized portion of the motor may be provided by effectively using the shape of the skirt portion which forms the cylindrical gap.

BRIEF DESCRIPTION OF THE DRAWINGS

The object and features of the present invention will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross sectional view showing a vane pump in accordance with a first embodiment of the present invention, taken along the line perpendicular to the rotation axis of the vane pump;

FIG. 2 is a cross sectional view depicting the vane pump including the rotation axis in accordance with the first embodiment of the invention;

FIG. 3 is an exploded perspective view illustrating the vane pump in accordance with the first embodiment of the invention;

FIG. 4 is an enlarged view of a part of the vane pump shown in FIG. 2;

FIG. 5 is a side view illustrating a rotary unit included in the vane pump in accordance with the first embodiment of the invention;

FIG. 6 is a side view depicting a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention;

FIG. 7 is a side view showing a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention;

FIG. 8 is a side view illustrating a rotary unit of a vane pump in accordance with a modification of the first embodiment of the present invention;

FIG. 9 is a side view depicting a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention;

FIG. 10 is a side view showing a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention;

FIG. 11 is a side view illustrating a rotary unit of a vane pump in accordance with a modification of the first embodiment of the present invention;

FIG. 12 is a side view depicting a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention;

FIGS. 13A and 13B are views showing a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention, in which FIG. 13A is a side view and FIG. 13B is a plan view;

FIG. 14 is a side view illustrating a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention;

FIG. 15 is a side view depicting a rotary unit of a vane pump in accordance with a modification of the first embodiment of the present invention;

FIG. 16 is a side view showing a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention;

FIG. 17 is a side view illustrating a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention;

FIGS. 18A and 18B are views depicting a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention, in which FIG. 18A is a side view and FIG. 18 b is a plan view;

FIG. 19 is a side view showing a rotary unit of a vane pump in accordance with a modification of the first embodiment of the invention;

FIGS. 20A and 20B are views illustrating a casing of a vane pump in accordance with a second embodiment of the present invention, in which FIG. 20A is a side view and FIG. 20B is a cross sectional view taken along the line XXb-XXb of FIG. 20A;

FIG. 21 is a cross sectional view depicting a casing included in the vane pump in accordance with a modification of the second embodiment of the invention;

FIG. 22 is a cross sectional view showing a casing of a vane pump in accordance with a modification of the second embodiment of the invention;

FIG. 23 is a cross sectional view illustrating a casing of a vane pump in accordance with a modification of the second embodiment of the invention;

FIG. 24 is a cross sectional view depicting a casing of a vane pump in accordance with a modification of the second embodiment of the invention;

FIG. 25 is a cross sectional view showing a casing of a vane pump in accordance with a modification of the second embodiment of the invention;

FIG. 26 is a cross sectional view illustrating a casing of a vane pump in accordance with a modification of the second embodiment of the invention;

FIGS. 27A and 27B are views depicting a casing of a vane pump in accordance with a third embodiment of the present invention, in which FIG. 27A is a plan view and FIG. 27B is a sectional view taken along the line XXVIIb-XXVIIb of FIG. 27A;

FIG. 28 is a cross sectional view showing a casing of a vane pump in accordance with a modification of the third embodiment of the invention;

FIG. 29 is a cross sectional view illustrating a casing of a vane pump in accordance with a modification of the third embodiment of the invention;

FIG. 30 is a cross sectional view depicting a casing of a vane pump in accordance with a modification of the third embodiment of the invention;

FIG. 31 is a cross sectional view showing a casing of a vane pump in accordance with a modification of the third embodiment of the invention;

FIG. 32 is a cross sectional view illustrating a casing of a vane pump in accordance with a modification of the third embodiment of the invention; and

FIG. 33 is a cross sectional view depicting a casing of a vane pump in accordance with a modification of the third embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, which form a part hereof. Further, the embodiments and modifications of the present invention include same elements. Therefore, the like parts will be designated by like reference characters, and redundant description of the same portions will be omitted.

First Embodiment

FIG. 1 is a cross sectional view showing a vane pump in accordance with the first embodiment of the present invention, taken along the line perpendicular to the rotation axis of the vane pump, FIG. 2 is a cross sectional view depicting the vane pump including the rotation axis, FIG. 3 is an exploded perspective view of the vane pump, FIG. 4 is an enlarged view showing a part of FIG. 2, and FIG. 5 is a side view illustrating a rotary unit included in the vane pump. Further, for the convenience of description, the upper side in FIGS. 2, 3 and 4 is indicated as the upper side of the rotation axis Ax, whereas the lower side is indicated as the lower side of the rotation axis Ax.

First, the configuration for sucking and discharging working fluid into and from the vane pump 1 will be described with reference to FIG. 1.

As shown in FIG. 1, the vane pump 1 in accordance with a first embodiment of the present invention includes a casing 2. An annular chamber 6 for receiving working fluid (liquid) therein is provided in the casing 2 to be positioned between the substantially cylindrical inner circumferential surface 3 a of an annular ring 3 and the outer circumferential surface 5 a of a substantially columnar base portion 5 of a rotary unit 4 which rotates around the rotation axis Ax. The width w of the annular chamber 6 is changed along the circumferential direction of the rotation axis Ax.

In the present embodiment, the center C of the inner circumferential surface 3 a and the rotation axis Ax are placed to be parallel to and offset from each other, so that the inner circumferential surface 3 a of the ring 3 is eccentric from the base portion 5 of the rotary unit 4. Thus, the annular chamber 6 has the minimum width at a right end of FIG. 1. The width w of the annular chamber 6 is gradually increased in the clockwise direction from the right end, so that the annular chamber 6 has the maximum width at the left end. Further, the width w of the annular chamber 6 is gradually reduced in the clockwise direction from the left end to the right end, so that the annular chamber 6 has the minimum width at the right end.

A plurality of slits 7 (four slits in the present embodiment) is formed in the base portion 5 to extend radially relative to the rotation axis Ax of the rotary unit 4 in such a way as to open outwardly in radial directions. Rectangular bar-shaped or strip plate-like vanes 8 are received in the respective slits 7 so that the vanes 8 cab be protruded from or retreated into the respective slits 7. In each slit 7, the corresponding vane 8 is forced outwardly in the radial direction by the centrifugal force exerted by the rotation of the rotary unit 4 and the pressure of the working fluid flowing into the rotation axis Ax side of the slits 7. Therefore, while the vanes 8 are in sliding contact with the inner circumferential surface 3 a, the vanes 8 rotate together with the rotary unit 4.

The annular chamber 6 is divided by the vanes 8 which are arranged at predetermined pitches in the circumferential direction of the annular chamber 6, thus forming as many pump rooms 9 as there are vanes 8 (four pump rooms in this embodiment). As the rotary unit 4 and the vanes 8 are rotated, the volume of each pump room 9 varies according to the change in the width w of the annular chamber 6. That is, each pump room 9 has the minimal volume at the right end of FIG. 1. Further, as the rotary unit 4 rotates in the rotating direction RD (the clockwise direction of FIG. 1), the volume of an associated pump room 9 is gradually increased. When the pump room 9 reaches the left end, the pump room 9 has the maximal volume. When the rotary unit 4 rotates further clockwise from the left end, the volume of the pump room 9 is gradually reduced. When the pump room 9 reaches the right end, the pump room 9 has the minimal volume.

That is, in the present embodiment, while the rotary unit 4 makes one revolution, the volume of the associated pump room 9 is being enlarged at the lower side in FIG. 1, and reduced at the upper side in FIG. 1. Thus, a suction opening 11 is provided at the inner circumferential surface 3 a of the ring 3 and the casing 2 (first casing 10) to face a section in which the volume of the pump room 9 is being enlarged, and a discharge opening 12 is provided at the inner circumferential surface 3 a of the ring 3 and the casing 2 to face a section in which the volume of the pump room 9 is being reduced. The suction opening 11 communicates with a suction passage 14 in a suction pipe 13 which protrudes from the sidewall of the first casing 10, and the discharge opening 12 communicates with a discharge passage 16 of a discharge pipe 15 which protrudes parallel to the suction pipe 13.

Thus, as shown in FIG. 1, when the rotary unit 4 rotates in the rotating direction RD, a pump room 9 defined between two neighboring vanes 8 moves from the right end to the left end while the volume thereof is being increased. Thus, the working fluid is fed from the suction passage 14 through the suction opening 11 to the pump room 9. Further, the pump room 9 moves from the left end to the right end while the volume thereof is being reduced. Thus, the working fluid is discharged from the pump room 9 through the discharge opening 12 to the discharge passage 16. The inflow and outflow of the working fluid relative to the pump rooms 9 are sequentially performed, so that the working fluid is continuously sucked and discharged by the vane pump 1.

Hereinafter, the configuration of the respective parts of the vane pump 1 in accordance with the present embodiment will be described in detail with reference to FIGS. 1 to 5.

As shown in FIG. 2, the slits 7 formed in the base portion 5 of the rotary unit 4 are closed by the lower wall portion 17 at the lower side in the axial direction. The vanes 8 reciprocate in the respective slits 7 while being in sliding contact with the lower wall portion 17. That is, in the present embodiment, the lower wall portion 17 corresponds to the guide wall. Further, communicating holes 17 a are formed at the lower wall portion 17 to communicate with radially inner portions of the slits 7. The working fluid of an exerting pressure is introduced into the slits 7 from a rear side of the lower wall portion 17 (the lower side in the axial direction) through the communicating holes 17 a. The exerting pressure has a value between the discharge pressure and the suction pressure.

The lower wall portion 17 has the shape of a disc which has at its center the rotation axis Ax and is perpendicular to the rotation axis Ax. A part of the lower wall portion 17 protrudes outwards from the outer circumferential surface 5 a of the base portion 5 in the form of a flange. Further, a cylindrical skirt portion 18 protrudes from the outer edge of the lower wall portion 17. The skirt portion 18 is concentric with the rotation axis Ax, and protrudes in a direction away from the base portion 5 (towards the lower side in the axial direction) to have a constant thickness.

The skirt portion 18 serves as a rotor of the motor 19 which drives the rotary unit 4, and includes a magnetized portion 18 a having N and S poles alternately in the circumferential direction to correspond to teeth 20 a of a stator core 20 around which coils are wound. At least a portion of the skirt portion 18 serving as the magnetized portion 18 a is made of a magnetic material. In this case, only a portion of the skirt portion 18 which faces the teeth 20 a may be made of a magnetic material (e.g. a hard magnetic material including ferrite magnet or samarium-cobalt magnet), or the entire skirt portion 18 may be made of a magnetic material. Alternatively, the entire rotary unit 4 may be made of a magnetic material. In this case, the rotary unit 4 or the skirt portion 18 may be formed using a mixture which is obtained by mixing powder or particle-type magnetic filler with resin material.

Further, as shown in FIGS. 1 and 3, recessed portions are provided on the outer circumferential surface 5 a of the base portion 5 at regular pitches in such a way as to be recessed inwardly in a radial direction. By the recessed portions, wings 5 b are formed. The wings 5 b are rotated together with the base portion 5 (rotary unit 4). When the wings 5 b face the suction opening 11, the performance of sucking the working fluid into the pump rooms 9 is increased. Meanwhile, when the wings 5 b face the discharge openings 12, the performance of discharging the working fluid from the pump rooms 9 is increased.

Further, as shown in FIG. 2, a bearing 22 for rotatably supporting a shaft is secured to the central portion of the base portion 5 (rotary unit 4). The bearing 22 may include a sliding bearing such as a metal bushing, or a rolling bearing such as a needle bearing.

Further, the rotary unit 4 is configured to be rotated around the rotation axis Ax in an internal space 2 a (see FIG. 2) defined by the casing 2. In the present embodiment, the casing 2 is provided with a first casing 10 which is positioned at the upper side in the axial direction (the upper sides in FIGS. 2 and 3), a second casing 23 which is positioned at the lower side in the axial direction (the lower sides in FIGS. 2 and 3), and a ring 3 which forms the outer circumferential surface of the annular chamber 6 (the inner circumferential surface 3 a of the ring 3).

As shown in FIG. 3, the ring 3 is provided with a cylindrical portion 3 b which forms the outer circumferential surface of the annular chamber 6, and a flange 3 c, which protrudes outwardly in the radial direction of the rotation axis Ax at the other side of the cylindrical portion 3 b in the axial direction. The ring 3 also includes ribs 3 d which form the sidewalls of the suction passage 14 and the discharge passage 16. The cylindrical portion 3 b and the ribs 3 d protrude from the disc-shaped flange 3 c in the axial direction of the rotation axis Ax such that their heights are almost equal to each other.

As shown in FIG. 2, the ring 3 is held in a recessed portion lob formed in the first casing 10. That is, the recessed portion 10 b has a recess to allow the cylindrical portion 3 b and the ribs 3 d of the ring 3 to be fitted therein. Further, the outer circumference 3 e of the flange 3 c of the ring 3 is in contact with the annular wall 23 a of the second casing 23 at the opposite side of the recessed portion 10 b. The ring 3 is interposed between the first casing 10 and the second casing 23, so that the ring 3 is secured in the axial direction of the rotation axis Ax.

An annular recessed portion 23 b and a recessed portion 23 c are formed in the second casing 23. The annular recessed portion 23 b receives the skirt portion 18 of the rotary unit 4, and the recessed portion 23 c receives a part of the bearing 22 of the rotary unit 4 which protrudes to the second casing 23 (the lower side in the axial direction, the lower side in FIG. 2 or 3).

A portion extending outwards diametrically from the annular wall 23 a provided on the outer circumference of the recessed portion 23 b serves as a contact surface with the first casing 10. An annular groove 23 d for an O-ring 34 is formed in the contact surface, and the O-ring 34 is fitted into the groove 23 d, thus sealing the junction between the first casing 10 and the second casing 23. Further, in addition to this junction, sealing members such as a gasket or an O-ring may be appropriately fitted into other junctions between components (e.g. the junction between the flange 3 c of the ring 3 and the first casing 10), thus improving sealing performance at respective junctions.

The shaft 21 is arranged between the lower wall portion 23 e of the recessed portion 23 c and the protruding portion 10 c of the first casing 10. Here, the center of the shaft 21 is the rotation axis Ax. The shaft 21 passes through the bearing 22 which is provided in the center of the rotary unit 4, and is supported by the bearing 22 to be freely rotatable.

Further, as shown in FIG. 2, an annular protruding portion 23 f is provided between the recessed portions 23 b and 23 c in such a way as to protrude from the opposite side of the rotary unit 4 (the lower side in the axial direction, the lower side in FIG. 2) to the rotary unit 4. The stator core 20 constituting the motor 19 is accommodated in an annular recessed portion 23 j which is provided in the backside of the protruding portion 23 f.

As shown in FIGS. 2 and 3, the stator core 20 is attached to the center of the surface 24 a of a substrate 24, and is provided with a cylindrical portion 20 b which is placed in the center of the stator core 20 to be concentric with the rotation axis Ax, and a plurality of teeth 20 a which extend radially from the cylindrical portion 20 b, with coils wound around the teeth 20 a.

Further, various electronic parts (not shown) are mounted on a backside 24 b (the lower side in the axial direction, the lower side in FIG. 2) which is opposite to the surface 24 a of the substrate 24 having the stator core 20, and a driving circuit of the motor 19 and other circuits are formed in the backside 24 b.

In the present embodiment, by the driving circuit formed in the substrate 24, the conduction state of the coil wound around each tooth 20 a is appropriately changed, so that the polarity of the outer circumference of each tooth 20 a is changed. Therefore, circumferential thrust force is applied to the magnetized portion 18 a (skirt portion 18) which is provided outward in the radial direction in such a way as to face the teeth 20 a, thus rotating the rotary unit 4. Therefore, among several components of the second casing 23, a partition wall 23 g interposed between the outer circumference of the stator core 20 (teeth 20 a) and the skirt portion 18 must be made of a material having magnetic permeability. For this reason, the partition wall 23 g or the entire second casing 23 are made of a material having magnetic permeability (e.g. stainless steel or resin material).

The substrate 24 is attached to the recessed portion 23 c to isolate the recessed portion 23 c from the opposite side of the rotary unit 4 (the lower side in the axial direction). Further, the substrate 24 is isolated from the opposite side of the rotary unit 4 (the lower side in the axial direction) by a substrate cover 25. Spacing projections 25 a are provided on the substrate cover 25 to ensure a space for holding the electronic parts between the substrate 24 and the substrate cover 25.

When looking in the axial direction of the rotation axis Ax, each of the first casing 10 and the second casing 23 has the shape of a square. Further, through holes 10 a (or 23 k) are formed in four corners of the casing 10 (or 23), so that screws 26 pass through the through holes 10 a and 23 k to fasten the casings 10 and 23 to each other. By inserting the screws 26 into the through holes 10 a and 23 k and the through holes 25 b formed in four corners of the substrate cover 25, and fastening nuts 27 to the screws 26, the vane pump 1 is assembled.

Further, the materials or manufacturing method of respective components which constitute the vane pump 1 are appropriately selected in consideration of abrasion-resistance, corrosion resistance, swelling resistance, formability, and machining accuracy, in addition to the above-mentioned ability to be magnetized or magnetic permeability.

Here, in the present embodiment, a fluid force generating portion 28 is provided on the rotary unit 4 to generate fluid force toward the upper side of the rotation axis Ax in the axial direction (the upper sides in FIGS. 2, 3 and 5) by the rotation of the rotary unit 4. The rotary unit 4 is pressed towards the first casing 10 disposed opposite to the lower wall portion 17.

As shown in FIG. 5, in the present embodiment, as the fluid force generating portion 28, slanting surfaces 28A which are inclined with respect to the rotating direction RD of the rotary unit 4 are provided on an end surface 18 b of the skirt portion 18 positioned at the lower side in the axial direction. Each slanting surface 28A is formed from a front edge 28F to a rear edge 28R thereof when viewed along the rotating direction RD in such a way as to be inclined upwardly from the lower side in the axial direction (the lower side in FIG. 5) to the upper side in the axial direction (the upper side in FIG. 5). That is, each slanting surface 28A has the front edge 28F and the rear edge 28R and is inclined upwards from the front edge 28F to the rear edge 28R. The front edge 28F and the rear edge 28R correspond to a trailing and a leading edge of the each slanting surface 28A rotating in the rotation direction RD. Thus, as the rotary unit 4 rotates, the working fluid contacting the slanting surfaces 28A exerts the fluid force F on the rotary unit 4, and pushes up the rotary unit 4 to the upper side in the axial direction (the upper side in FIG. 5).

Further, as shown in FIG. 4, a thrust support unit 29 is provided on the first casing 10 to slidably support the rotary unit 4 that is rotated while receiving the fluid force F (thrust force) acting toward the upper side in the axial direction. Specifically, a portion of the first casing 10 in which the shaft 21 is inserted and supported is protruded toward the lower side in the axial direction, thereby forming the protruding portion 10 c. The bottom surface 4 b of the recessed portion 4 a formed in the central portion of the rotary unit 4 (base portion 5) is in contact with a most-protruding surface 10 d of the protruding portion 10 c via a washer 30. In the present embodiment, the thrust support unit 29 is provided with a washer 30, which is in contact with an axial end surface 22 a (which is partially exposed to the bottom surface 4 b of the recessed portion 4 a) of the bearing 22 provided on the central portion of the rotary unit 4, so that abrasion resistance is easily increased.

That is, such a configuration allows the abrasion resistance in this region to be adjusted by the specifications (e.g., material, dimensions, hardening treatment and the like) of a sliding contact portions between the washer 30 and the bearing 22, and the specifications of the main body (e.g., base portion 5, lower wall portion 17 and the like) of the rotary unit 4 may be selected in consideration of lightness, slidability of other sliding portions, corrosion resistance, and the like.

Further, as shown in FIG. 4, in the thrust support unit 29, the diameter D2 of the sliding portion is set to be smaller than the diameter D1 of the base portion 5. In the case where the fluid force generating portion 28 is provided as in the present embodiment, a top surface 5 c of the base portion 5 is in sliding contact with the first casing 10, and sliding resistance may be undesirably increased unless the through support portion is provided. Further, in the present embodiment, the diameter D2 of the sliding portion is set to be smaller than the diameter D1 of the base portion 5, so that the sliding resistance and friction can be further reduced.

Further, as shown in FIG. 2, a small gap 31 is arranged between a top surface 17 b of the lower wall portion 17 and a bottom surface 3 f of the ring 3, so that the leakage flow rate from the gap between the surfaces 17 b and 3 f is reduced to be as small as possible. Further, another washer 30 is disposed on the lower side of the bearing 22 in the axial direction.

As described above, in the present embodiment, the rotary unit 4 is pushed up to the upper side of the rotation axis Ax by the fluid force generating portion 28. Such a configuration allows the rotary unit 4 to come in contact with the upper side of the casing 2 in the axial direction (i.e. the first casing 10), thus preventing the rotary unit 4 from reciprocating during rotation. Further, such a configuration prevents vibration or noise resulting from the reciprocating motion of the rotary unit 4.

Further, as shown in FIG. 4, a gap g between the top surface 5 c of the base portion 5 and a bottom surface 10 e of the first casing 10 can be more easily and precisely designated by the dimension d1 of the rotary unit 4 and the dimension d2 of the first casing 10. By increasing or changing the gap, the increase in the leakage flow rate and the reduction in pump efficiency can be prevented, and deviations (individual variation) of the discharge amount of the vane pump 1 can be reduced.

Further, the lower wall portion 17 is provided to slidably support the vanes 8 at the lower side in the axial direction, thus preventing the vanes 8 from moving to the lower side in the axial direction, and preventing vibration or noise due to the axial reciprocation motion of the vanes 8, and preventing the leakage flow rate from being increased, therefore preventing the pump efficiency from being reduced. Such a configuration moves the vanes 8 to the upper side in the axial direction together with the rotary unit 4.

Further, in the present embodiment, as the fluid force generating portion 28, the slanting surfaces 28A which are inclined in the rotating direction RD of the rotary unit 4 are provided. Therefore, the fluid force generating portion 28 can be obtained using a relatively simple configuration. Especially, in the present embodiment, it is easy to increase the area of the end surface 18 b of the skirt portion 18 having the slanting surfaces 28A at the lower side in the axial direction. Further, since it is easy to obtain a large gap between the second casing 23 and the skirt portion 18, desired fluid force can be more easily generated.

Further, in the present embodiment, as shown in FIG. 2, annular gaps 32 and 33 are provided between the skirt portion 18 and the second casing 23. The gap 32 is provided between the outer circumferential surface 18 c of the skirt portion 18 and the inner circumferential surface 23 h of the annular wall 23 a of the second casing 23, while the gap 33 is provided between the outer circumferential surface 23 i of the partition wall 23 g and the inner circumferential surface 18 d of the skirt portion 18. By providing the skirt portion 18, the cylindrical gaps 32 and 33 between the skirt portion 18 and the second casing 23 are formed in a predetermined range of the rotation axis Ax in the axial direction. By appropriately setting the size of a clearance of a relatively fine gap, the flow resistance of working fluid which leaks from the pump room 9 (pump room 9 provided on the upper side in FIG. 1) performing a discharge stroke to the pump room 9 (pump room 9 provided on the lower side in FIG. 1) performing a suction stroke through the lower side of the base portion 5 in the axial direction is increased, thereby reducing the leakage flow rate.

Further, since the gaps (fine gaps) 32 and 33 are concentric with the rotation axis Ax, even when the rotary unit 4 moves to the upper side in the axial direction, the leakage flow rate of the working fluid between the lower side of the rotary unit 4 in the axial direction and the second casing 23 can be reduced.

The skirt portion 18 serves as a rotor constituting the motor 19. In the present embodiment, by effectively using the structures of the skirt portion 18 serving as the rotor and its surrounding parts, e.g., by using the cylindrical gaps (fine gaps) 32 and 33 formed at the outside and the inside portion of the skirt portion 18 in the radial direction, the leakage flow rate can be efficiently reduced.

(Modifications of the Slanting Surfaces as the Fluid Force Generating Portion Provided on the Rotary Unit)

FIGS. 6 to 12 are side views illustrating the modifications of slanting surfaces. The drawings illustrate modifications wherein the slanting surfaces 28A serving as the fluid force generating portion 28 are provided on the end surface 18 b of the skirt portion 18 of the rotary unit 4 provided on the lower side (lower sides in FIGS. 6 to 12) in the axial direction. As shown in the respective drawings, the specifications (position, shape, angle, depth, width, pitch, curvature, etc.) of the slanting surfaces 28A can be appropriately changed. In these configurations as well, as the rotary unit 4 is rotated, the fluid force F of the working fluid acts on the slanting surfaces 28A to push the rotary unit 4 up to the upper side in the axial direction. The rotary unit 4 is rotated while being pressed towards the thrust support unit 29 of the first casing 10. Thus, the modifications achieve the same effect as in the first embodiment.

FIGS. 13A and 13B are views illustrating another modification of slanting surfaces, in which FIG. 13A is a side view and FIG. 13B is a plan view seen from the arrow A shown in FIG. 13A. Further, FIGS. 14 to 17 are side views illustrating other modifications of slanting surfaces. FIGS. 13A through 17 illustrate the modifications wherein the slanting surfaces 28A serving as the fluid force generating portion 28 are provided on the outer circumferential surface 18 c of the skirt portion 18. In the modifications, recessed portions 18 e of a predetermined depth are provided in the outer circumferential surface 18 c, and an end surface 18 f of each recessed portion 18 e provided on the upper side in the axial direction (the upper sides in FIG. 13A and FIGS. 14 to 17) is formed as the slanting surface 28A.

As shown in respective drawings, the specifications (position, shape, angle, depth, width, pitch, curvature, etc.) of the slanting surfaces 28A can be appropriately changed. In these configurations as well, as the rotary unit 4 is rotated, the fluid force F of the working fluid acts on the slanting surfaces 28A to push the rotary unit 4 up to the upper side in the axial direction. The rotary unit 4 is rotated while being pressed towards the thrust support unit 29 of the first casing 10. Thus, the modifications achieve the same effect as in the first embodiment.

(Modification of the Fluid Force Generating Portion Provided on the Rotary Unit)

FIGS. 18A and 18B are views illustrating the modification of the fluid force generating portion, in which FIG. 18A is a side view and FIG. 18B is a plan view seen along the arrow B shown in FIG. 18A. In the modification, wings 28B serving as the fluid force generating portion 28 are provided at the bottom end of the skirt portion 18 of the rotary unit 4 placed at the lower side (the lower side in FIG. 18A) in the axial direction. Each wing 28B is of a flat plate shape which is inclined relative to the rotating direction RD of the rotary unit 4. An elevation angle α is provided to each wing 28B to generate a predetermined lifting force by the counter flow of the working fluid generated as the rotary unit 4 rotates. That is, each wing 28B is inclined upward (toward the upper side in FIG. 18A) from its front edge to rear edge when viewed along the rotating direction RD. In these configurations as well, as the rotary unit 4 rotates, the fluid force F of the working fluid acts on the wings 28B to push up the rotary unit 4 to the upper side in the axial direction. The rotary unit 4 is rotated while being pressed towards the thrust support unit 29 of the first casing 10. Thus, the modification achieves the same effect as in the first embodiment.

(Another Modification of the Fluid Force Generating Portion Provided on the Rotary Unit)

FIG. 19 is a side view illustrating another modification of the fluid force generating portion. In the modification, a spiral groove 28C serving as the fluid force generating portion is provided on the outer circumferential surface 18 c of the skirt portion 18 of the rotary unit 4. The groove 28C is formed in such a way as to be inclined upwardly (toward the upper side in FIG. 19) from a trailing side 18T of the rotating skirt portion 18 to a leading side 18L. As the rotary unit 4 rotates in the rotating direction RD, the counter flow of working fluid in the groove 28C is guided towards the lower side in the axial direction. Thus, in these configurations as well, as the rotary unit 4 is rotated, the fluid force F of the working fluid acts on the groove 28C to push up the rotary unit 4 to the upper side in the axial direction. The rotary unit 4 is rotated while being pressed towards the thrust support unit 29 of the first casing 10. Thus, the modification achieves the same effect as in the first embodiment.

(Second Embodiment

FIGS. 20A and 20B are views illustrating a casing (the second casing) included in a vane pump according to the second embodiment of the present invention, in which FIG. 20A is a plan view seen from the upper side in the axial direction, and FIG. 20B is a sectional view taken along the line XXb-XXb of FIG. 20A.

In the present embodiment, protrusions 28D are provided on a portion of the second casing 23 opposite to the rotary unit 4 in such a way as to protrude toward the rotary unit 4. The second embodiment is different from the first embodiment in that the protrusions 28D are used as the fluid force generating portion 28 exerting the fluid force on the rotary unit 4 to push same towards the upper side in the axial direction. Except for the difference, the general configuration of the second embodiment remains the same as the first embodiment.

In detail, the protrusions 28D are provided on the bottom surface 23 m of the recessed portion 23 b of the second casing 23 to protrude towards the skirt portion 18 (rotary unit 4), i.e., towards the upper side in the axial direction (the upper side in FIG. 20A). That is, the protrusions 28D are provided on the portion disposed at the lower side of the end surface 18 b, which is provided at the lower side of the skirt portion 18 (rotary unit 4) in the axial direction. The protrusions 28D are provided on a plurality of places along the circumferential direction of the rotation axis Ax (four places, each at the angular interval of 90 degrees in the present embodiment).

As shown in FIG. 2, an annular space is formed between the end surface 18 b of the skirt portion 18 and the bottom surface 23 m of the recessed portion 23 b to receive working fluid therein. As the rotary unit 4 rotates, the working fluid is pulled to the rotating skirt portion 18 by the viscosity of the working fluid, and flows in the rotating direction RD of the rotary unit 4. Since the protrusions 28D form narrow portions to the flow of the working fluid, the pressure of the working fluid is increased at a place provided with each protrusion 28D (i.e. the place from the narrowest portion to the edge of the protrusion 28D at the upstream side in the rotating direction RD). By this pressure, fluid force F acts on the end surface 18 b of the skirt portion 18 to push the rotary unit 4 toward the upper side in the axial direction.

Particularly, in the present embodiment, each protrusion 28D is provided with a slanting surface 28Da, wherein each slanting surface 28Da is inclined upwards from a front edge 28DF to a rear edge 28DR thereof when viewed along the rotating direction RD. That is, when viewed along the rotating direction RD, the slanting surface 28Da is inclined upwards, i.e., from the second casing 23 side to the first casing 10 side. Thus, the flow of the working fluid is angled to the upper side in the axial direction along the slanting surface 28Da, so that the fluid force F can more efficiently act.

In this configuration, since the fluid force generating portion 28 is provided on the second casing 23, the rotary unit 4, which is subjected to fluid force F acting towards the upper side in the axial direction by the fluid force generating portion 28, is rotated while being pressed towards the thrust support unit 29 of the first casing 10. Therefore, the second embodiment achieves the same effect as in the first embodiment.

Further, with such configuration, the protrusions 28D are provided on the second casing 23, so that the fluid force generating portion can be obtained in a relatively simple configuration.

(Modification of the Fluid Force Generating Portion Provided on the Casing (bottom Surface 23 m))

FIGS. 21 through 26 are sectional views illustrating second casings having slanting surfaces in accordance with the modifications, and are sectional views taken at the same position as the line XXb-XXb of FIG. 20. The drawings illustrate the modifications wherein the protrusions 28D serving as the fluid force generating portion 28 are provided on the recessed portion 23 b of the second casing 23.

As shown in the respective drawings, the specifications (position, shape, angle, depth, width, pitch, curvature, etc.) of the protrusions 28D and the slanting surfaces 28Da provided at the front side thereof when viewed along the rotating direction RD may be appropriately changed. Further, as shown in FIG. 26, each protrusion 28D need not be a slanting surface but may rather be a horizontal surface. In these configurations as well, as the rotary unit 4 is rotated, the fluid force F of the working fluid contacting the protrusions 28D acts on the rotary unit 4 to push it up to the upper side in the axial direction. The rotary unit 4 is rotated while being pressed towards the thrust support unit 29 of the first casing 10. Thus, the modifications achieve the same effect as in the second embodiment.

Third Embodiment

FIGS. 27A and 27B are views illustrating a second casing included in a vane pump in accordance with the third embodiment of the present invention, in which FIG. 27A is a plan view of the second casing when it is seen from the upper side in the axial direction, and FIG. 27B is a sectional view taken along line XXVIIb-XXVIIb of FIG. 27A.

In the present embodiment, protrusions 28E are provided on the portion of the second casing 23 opposite to the rotary unit 4 in such a way as to protrude towards the rotary unit 4. The third embodiment is different from the first embodiment in that the protrusions 28E are used as the fluid force generating portion 28 exerting the fluid force on the rotary unit 4 to push same towards the upper side in the axial direction. Except for the difference, the general configuration of the third embodiment remains the same as the first embodiment.

In detail, the protrusions 28E are provided on the protruding portion 23 f of the second casing 23 to protrude towards the lower wall portion 17 (rotary unit 4), that is, the upper side in the axial direction (the upper side in FIG. 27B). The protrusions 28E are provided on a plurality of places along the circumferential direction of the rotation axis Ax (four places, each at the angular interval of 90 degrees in this embodiment).

As shown in FIG. 2, an annular space is formed between the lower wall portion 17 and the protruding portion 23 f to receive working fluid therein. As the rotary unit 4 rotates, the working fluid in the annular space is pulled to the lower wall portion 17 which is rotated by the viscosity of the working fluid, and flows in the rotating direction RD of the rotary unit 4. Since the protrusions 28E form narrow portions to the flow of the working fluid, the pressure of the working fluid is increased at a place provided with each protrusion 28E (i.e. at the place from the narrowest portion to the edge of the protrusions 28E at the upstream side in the rotating direction RD). By the pressure, fluid force F acts on the lower wall portion 17, that is, the rotary unit 4 such that it is moved to the upper side in the axial direction.

Particularly, in the present embodiment, each protrusion 28E is provided with a slanting surface 28Ea, wherein each slanting surface 28Ea is inclined upwards from a front edge 28EF to a rear edge 28ER thereof when viewed along the rotating direction RD. That is, when viewed along the rotating direction RD, the slanting surface 28Ea is inclined upwards, i.e., from the second casing 23 side to the first casing 10 side. Thus, the flow of the working fluid is angled to the upper side in the axial direction along the slanting surface 28Ea, so that the fluid force F can more efficiently act.

Therefore, in this configuration, the fluid force generating portion 28 is provided on the second casing 23. Thus, the rotary unit 4, which is subjected to fluid force F acting towards the upper side in the axial direction by the fluid force generating portion 28 is rotated while being pressed towards the thrust support unit 29 of the first casing 10. Therefore, the third embodiment achieves the same effect as in the first and second embodiments.

Further, with such configuration, the protrusions 28E are provided on the second casing 23, so that the fluid force generating portion can be obtained in a relatively simple construction.

(Modifications of the Fluid Force Generating Portion Provided on the Casing (protruding Portion 23 f))

FIGS. 28 through 33 are sectional views illustrating second casings having slanting surfaces in accordance with the modifications, and are sectional views taken at the same position as line XXVIIb-XXVIIb of FIG. 27A. The drawings illustrate the modifications wherein the protrusions 28E serving as the fluid force generating portion 28 are provided on the protruding portion 23 f of the second casing 23. As shown in the respective drawings, the specifications (position, shape, angle, depth, width, pitch, curvature, etc.) of the protrusions 28E and the slanting surfaces 28Ea provided at the front side thereof when viewed along the rotating direction RD may be appropriately changed.

Further, as shown in FIG. 33, each protrusion 28E need not be a slanting surface but may rather be a horizontal surface. In these configurations as well, as the rotary unit 4 is rotated, the fluid force F of the working fluid contacting the protrusions 28E acts on the rotary unit 4 to push it up to the upper side in the axial direction. The rotary unit 4 is rotated while being pressed towards the thrust support unit 29 of the first casing 10. Thus, the modifications achieve the same effect as in the third embodiment.

Although the embodiments and modifications of the present invention have been described for illustrative purposes, the present invention is not limited thereto and various changes and modifications may be made. For example, the detailed configuration of the rotary unit, ring, or casing of the vane pump is not limited to the above-mentioned embodiments. Further, the rotary unit may be pressed towards a side opposite to the side described in the embodiments by the fluid force generating portion. That is, the rotary unit may be pressed towards the casing located on the same side as the motor. Further, the fluid force generating portion may be provided on both of the rotary unit and the casing. Furthermore, the skirt portion may not be installed steplessly to lower wall portion serving as the guide wall, as in the embodiments of the present invention. A step may be provided between the skirt portion and a flange radially protruding outwardly from the guide wall and the base portion, or the skirt portion may protrude directly from the base portion. Further, each wing may be formed to have the shape of a general wing which is dull at its upstream side and is sharp at an edge of its downstream side. The spiral projection may be used instead of the spiral groove. Further, the slanting surface or the spiral groove or projection may be discontinuously formed.

While the invention has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims. 

1. A vane pump comprising: a plurality of slits which are formed in a base portion of a rotary unit rotating in a casing and extend radially from a rotation axis of a rotary unit to be opened outwardly in a radial direction; a vane received in each of the slits to be protruded from or retreated into the slit; an annular chamber formed around the base portion in the casing; a plurality of pump rooms formed by defining the annular chamber by using the plurality of vanes, the vane pump being operated to discharge fluid sucked into an associated pump room by rotating the rotary unit and thereby periodically increasing or reducing volume of the pump rooms; and a fluid force generating portion provided on at least one of the rotary unit and the casing to generate fluid force to the upper side in an axial direction of the rotation axis by rotation of the rotary unit.
 2. The vane pump of claim 1, wherein a guide wall is provided on the rotary unit and placed on the lower side in the axial direction of the rotation axis to be in sliding contact with an associated vane.
 3. The vane pump of claim 1, further comprising: a thrust support unit for slidably supporting the rotary unit against the casing, the rotary unit being rotated by the fluid force applied to the upper side in the axial direction, wherein a diameter of a sliding portion of the thrust support unit is smaller than a diameter of the base portion.
 4. The vane pump of claim 1, wherein the fluid force generating portion is provided on the rotary unit, and includes a slanting surface which is inclined with respect to a rotating direction of the rotary unit.
 5. The vane pump of claim 1, wherein the fluid force generating portion is provided on the rotary unit, and includes a wing brought into contact with a counter flow of the fluid resulting from rotation of the rotary unit.
 6. The vane pump of claim 1, wherein the fluid force generating portion is provided on the rotary unit, and includes a spiral projection or groove formed around the rotation axis.
 7. The vane pump of claim 1, wherein the fluid force generating portion is provided on the casing, and includes a protrusion which is opposite to the rotary unit in such a way as to protrude towards the rotary unit.
 8. The vane pump of claim 1, wherein the rotary unit includes a cylindrical skirt portion which is concentric with the rotation axis and protrudes towards the lower side in the axial direction, and a cylindrical gap is formed between the skirt portion and the casing.
 9. The vane pump of claim 8, further comprising: a magnetized portion provided on the skirt portion; a stator core including a coil provided inside the skirt portion; and a motor having the magnetized portion and the stator core which are arranged in a radial direction of the rotation axis of the rotary unit to be spaced apart from each other. 